The present patent application claims priority under 35 U.S.C. 119 (a)-(d) of German Patent Application No. 100 37 269.4, filed Jul. 28, 2000.
The invention provides molded articles containing barrier films, which are prepared by an insert molding process.
Observation of the new legal regulations relating to the maximum permissible total emissions from motor vehicles requires the development of new system solutions for the structural group of plastic materials used in motor vehicles. Determining the total emissions is typically performed using the so-called SHED test (Sealed Housing for Evaporate Determination test) in which the total emissions from a complete motor vehicle are determined under defined conditions. These total emissions thus take account not only of the hydrocarbon emissions (HC emissions) from the fuel system and engine surroundings and in particular the fuel tank, but also emissions from the car body and the operating substances, and also from internal fittings, the electrical system and tires.
The technology to produce, for example, plastics fuel tanks (PFTs) has been constantly further developed in recent years, with regard to the maximum hydrocarbon emissions, against the background of ever more stringent legal requirements.
It is known that PFTs can be produced by the blow molding process, in which an extruded tube (premolding) is generally pressed into mold using compressed air and solidified there. To improve the HC barrier effect, specific barrier layers, for example made of ethylenevinyl alcohol, are incorporated in the layered composite by a coextrusion process. xe2x80x9cBarriertechnologien: Ein Beitrag zur Emmissionsreduzierung von Kraftstoffanlagenxe2x80x9d, W. Klee, U. Karsch, T. Kempen, p. 309; Conference proceedings for the specialist conference xe2x80x9cKunststoffe im Automobilbauxe2x80x9d 2000.
However, these molded items still have considerable emissions. In addition it is a disadvantage of the blow molding process that the internal faces of the tanks are difficult to access when fitting connecting pieces and functional parts and also that they have long cooling times since rapid cooling can occur at only one face. As a result of the actual mode of operation, it is not possible to produce ribs and undercuts when blow molding. Targeted adjustment of a change in wall thickness is possible to only a limited extent via the wall thickness of the premolding or the blow-up ratio.
An alternative is the use of a second skin which surrounds the tank and has adsorbents on its inner face, which act as spacers. The space in between the tank and the outer shell is flushed out with air being sucked in by the motor (DE-A 41 42 016). The disadvantages here are the costly technical procedure and the necessity for adsorbents.
The object of the invention is to provide a process and molded items which can be produced by this process, wherein the molded items ensure reduced emissions, in particular of hydrocarbons and of substances contained in plastics, and in addition which do not have the mechanical/technical disadvantages described above. accordance with the present invention, there is provided a molded plastic article comprising a barrier film wherein said article is prepared by a process comprising:
(a) providing a barrier film comprising at least one organic polymeric layer, said barrier film having a first surface and a second surface;
(b) placing said barrier film in a mold such that the first surface of said barrier film is in contact with at least a portion of the interior surface or surfaces of said mold;
(c) injecting a polymer and/or polymer precursor (e.g., a molten thermoplastic polymer and/or a thermosetting polymer composition) into said mold, the injected polymer and/or polymer precursor contacting the second surface of said barrier film; and
(d) removing said molded plastic article from said mold.
Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be under stood as modified in all instance by the term xe2x80x9cabout.xe2x80x9d